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<html lang="en">
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        <meta charset="UTF-8">
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        <title> 计算器</title>
        <script src="../js/calc.js"></script>
        </head>
        <body>
            <table >
                <thead >计算器</thead>
                <tr colspan="4">
                    <td colspan="4"><input type"=buton"></td>
                    </tr>
                    <tr >
                        <td><input  type="button">AC </td>
                        <td><input  type="button"></td>
                        <td><input  type="button"></td>
                        <td><input  type="button"></td>
                        </tr>
                        <tr >
                            <td><input type="button"></td>
                            <td><input type="button"></td>
                            <td><input type="button"></td>
                            <td><input type="button"></td>
                            </tr>
                            <tr >